Physics

A child is standing with folded hands at the centre of a platform rotating about its central axis. The kinetic energy of the system is K. The child now stretches his arms so that the moment of inertia of the system becomes 3/2 of the initial moment of inertia. The kinetic energy of the system is now

If the absolute temperature of hot black body is raised by 2%, by how much percentage rate of heat energy radiated would be increased nearly?

Two moles of helium gas are taken over the cycle ABCDA as shown below in P-T diagram. Assuming the gas to be ideal, the work done on the gas in taking from A to B is

An incompressible liquid flows through a horizontal tube as shown in the following figure. The velocity v of the fluid is

A point mass m is placed at a distance 2R from the centre of the shell of mass M and radius R. The gravitational force exerted by shell on the point mass is

When a soap bubble is illuminated by source of white light, it appears coloured. This is due to

Activity of radioactive element decrease to one-fourth of original activity R₀ in 16 years, after further 16 years, its activity will be  

The distance of closest approach of an alpha particle fired towards gold nucleus with kinetic energy k is r₀. The distance of closest approach when the alpha particle is fired towards same nucleus with kinetic energy 4k will be

The current flow through the resistance in the given circuit is : (Cut-off voltage for both diodes is 0.7 V)

A n-p-n transistor can be used as